Thermosensitive delayed action means for ordnance missiles



J.-J. FURLANI Jan. 14, 1969 THERMOSENSITIVE DELAYED ACTION MEANS FOR ORDNANGE MISSILES Filed Aug. 25, 1958 INVENTOR u. ummlw United States Patent 2 Claims The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a relatively simple, compact, and inexpensive means to accomplish self-destruction of a projectile as a result of aerodynamic heating.

When missiles such as bullets or rockets are fired from either the ground or from friendly aircraft at enemy aircraft, the curved trajectory of the missile finally causes it to strike the ground if it misses the enemy aircraft. Oftentimes the missile would strike friendly troops or installations as a result of its missing the enemy target, and therefore, some means is needed for causing a missile to destroy itself before it hits the ground when it misses the air target.

In order to provide safe handling of the missile before it is fired, the means which finally destroys it.should be responsive to some condition which inevitably occurs between the missile launcher and the ground. Some missiles such as bullets are relatively small and inexpensive and therefore it is desirable if the means for effecting self-destruction also be small and inexpensive.

It has been found that during the flight of bullets or rockets, air friction passing over the outer surface of the missile causes the missile to increase in temperature. This phenomenon is generally known in the art as aerodynamic heating.

'It is an object of this invention to provide a compact, inexpensive, and relatively simple system for effecting self-destruction of a missile by utilizing aerodynamic heat produced by normal missile flight.

It is a further object of this invention to provide a system which will finally effect self-destruction of the missile at some predetermined time after the missile has been fired or launched.

According to this invention, aerodynamic heat developed in the outer surface of the fired missile is utilized to ignite an explosive which destroys the missile some predetermined time after it has been fired or launched.

The specific nature of the invention, as well as other objects, uses and advantages thereof, will clearly appear from the following description and from the accompanying drawings, in which:

The drawing shows a sectional side view of a portion of a missile which has a temperature sensitive material encased in the nose.

As shown in the drawing, the forward tip of missile comprisses a body 11 and a nose 12. The rearward surfaces of nose 12 mate with the forward surfaces of body portion 11. The particular configuration of nose 12 is immaterial and any desired shape may be used. Body 11 has a circular groove 13, which receives for rotative movement spherical ball rotor 14, having detonator 19 encased therein. The longitudinal axis of detonator 19 is inclined at an angle to the rotational axis of missile 10. In such a position the detonator is in an unarmed or safe position. Spring 16 is affixed within body 11 at spring end 17, and has a free end 18 which can move into cavity 11a in response to centrifugal forces developed by rotation of missile 10. When spring 16 is out of "ice engagement with flat surface 15, as a result of centrifugal force, rotor 14 is weighted so as to rotate counterclockwise, as viewed in the drawing, until the longitudinal axis of detonator 19 is coaxial to the axis of missile rotation. This position is the armed or unsafe position. As will be evident to those in the art, detonator 19 when initiated will cause detonation of a more powerful main explosive charge (-not shown) located in the missile body so that complete destruction of the missile is insured.

The above-described means for arming in response to centrifugal force is merely one example of a suitable system for use in missile which rotates at some high rate of speed. It should be evident to those skilled in the art, that other means responsive to either centrifugal force or responsive to acceleration forces produced on firing may also be employed to move detonator 19 to the armed position.

Nose 12 has bores 24, 21 and 24 therein. Bores 20 and 21 tightly receive circular pins 22- and 23, respectively, which protrude from forwardmost surface body 11. Pins 22 and 23 hold nose 12 tightly to body 11 at all times. Coaxially positioned in nose 12 is bore 24, which is tapered at its forwardmost end to form a tapered wall 25. The tapered Wall 25 is substantially parallel to, and slightly spaced from, the outer skin surface 26 of nose 12. Bore 24 is provided at its rearward end with a larger circular opening 27, into which a thin circular metal shim 28 is held to body 12 by bent-over ends 29. Shim 28 seals the rearward opening of bore 24, as shown. The forwardmost end bore 24 is filled with a quantity of temperature sensitive material 30, such as powdered silver oxalate. The rearward portions of material 30 contact forward portions of a heat powder 31 such as zirconium, which can be ignited by temperature sensitive material 30. Heat powder 31 burns slowly and forms a powder train time delay. Rearward portions of heat powder 31 contact forward portions of powdered explosive 32, so that the explosive can be detonated when the burning of the heat powder train reaches the forward portions of the powdered explosive. Shim 28 is thin enough so that explosive 32 can explode through the shim and into bore 33 thereby detonating detonator 19 if the detonator has been rotated by centrifugal force to the armed position.

When missile 10 is fired, air passing over skin 26 creates friction and aerodynamic heat. is developed in nose 12. Heat developed on the outer surface of nose 12 flows through walls 25 to temperature sensitive material 30. As soon as walls 25 reach the ignition temperature of any portion of material 30' all of the material will instantly ignite or explode. Explosion of material 30 causes time delay train 31 to burn, thereby igniting explosive 32 after some predetermined interval of time. The time interval, of course, should be of a sufficient duration so that the missile will not destroy itself until it is beyond the area of the air target.

For a given missile, the time required before the temperature of the skin reaches some predetermined value sufficient to cause ignition of temperature sensitive material 30 after the missile has been launched or fired, is substantially constant. Hence it is possible to predict fairly accurately the interval of time which will elapse between firing of the missile and ignition of the temperature sensitive material. The time delay produced by time delay train 31 is used in order to attain a longer time interval between firing and self-destruction of those missiles which miss the target. Destruction of the missile should occur before it can strike friendly installations or troops on the ground.

While the above-described system produces self-destruction of a missile, the explosion of explosive 32 could 3 also be utilized to drive switches or linkages which would accomplish arming of the missile.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

I claim as my invention:

1. In an elongated ordnance missile having a body and a nose affixed thereto at one end thereof, means for destroying said missile at a predetermined time, said means including a bore within said nose, said bore being coaxial with the longitudinal axis of said missile, the forwardmost end of said bore being adjacent the forwardmost end of said missile and spaced from the outer surface of said missile; a temperature sensitive powdered material contained in said forwardmost end of said bore, said temperature sensitive material having forward and rearward portions in said bore and being of a type which explodes when any portion of the material reaches a predetermined temperature, said predetermined temperature corresponding to that which is produced by flight of the missile for some predetermined time; a time delay powder train in said bore having forward and rearward portions, forward portions of said powder train contacting rearward portions of said temperature sensitive material; an explosive charge contained in said bore the rearward portion of said lbore being closed by a closure means, forward portions of said explosive charge contacting rearward portions of said powder train, rearward portions of said explosive charge contacting said closure means; and a detonator mounted for rotation in said body and positioned so as to align with said closure means and said explosive charge upon rotation of said missile about its longitudinal axis, said temperature sensitive material igniting said time delay powder train as a result of said nose reaching said predetermined temperature, said time delay powder train detonating said explosive charge, detonation of said explosive charge exploding through said closure means and causing the aligned detonator to explode and thusly initiate destruction of said missile.

2. The invention as recited in claim 1, wherein said temperature sensitive material consists of powdered silver oxalate.

References Cited UNITED STATES PATENTS 1,088,025 2/1914 Johnson 102-87 1,107,593 8/1914 Down 102-87 1,126,415 1/1915 Dickinson 102-87 1,301,382 4/1919 Buckingham 102-87 2,782,717 2/1957 -Burri 102-71 2,824,518 2/ 1958' Piskorski 102-79 2,838,999 6/1958 Corsi 102-72 2,850,978 9/1958 Franklin 102-702 SAMUEL FEINBERG, Primary Examiner. G. H. GLANSMAN, Assistant Examiner. 

1. IN AN ENLONGATED ORDNANCE MISSILE HAVING A BODY AND A NOSE AFFIXED THERETO AT ONE END THEREOF, MEANS FOR DESTROYING SAID MISSILE AT A PREDETERMINED TIME, SAID MEANS INCLUDING A BORE WITHIN SAID NOSE, SAID BORE BEING COAXIAL WITH THE LONGITUDINAL AXIS OF THE SAID MISSILE, THE FORWARDMOST END OF SAID BORE BEING ADJACENT THE FORWARDMOST END OF SAID MISSILE AND SPACED FROM THE OUTER SURFACE OF SAID MISSILE; A TEMPERATURE SENSITIVE POWDERED MATERIAL CONTAINED IN SAID FORWARDMOST END OF SAID BORE, SAID TEMPERATURE SENSITIVE MATERIAL HAVING FORWARD AND REARWARD PORTIONS IN SAID BORE AND BEING OF A TYPE WHICH EXPLODED WHEN ANY PORTION OF THE MATERIAL REACHES A PREDETERMINED TEMPERATURE, SAID PREDETERMINED TEMPERATURE CORRESPONDING TO THAT WHICH IS PRODUCED BY FLIGHT OF THE MISSILE FOR SOME PREDETERMINED TIME; A TIME DELAY POWDER TRAIN IN SAID BORE HAVING FORWARD AND REARWARD PORTIONS, FORWARD PORTIONS OF SAID POWDER TRAIN CONTACTING REARWARD PORTIONS OF SAID TEMPERATURE SENSITIVE MATERIAL; AN EXPLOSIVE CHARGE CONTAINED IN SAID BORE THE REARWARD PORTION OF SAID BORE BEING CLOSED BY A CLOSURE MEANS, FORWARD PORTIONS OF SAID EXPLOSIVE CHARGE CONTACTING REARWARD PORTIONS OF SAID POWDER TRAIN, REARWARD PORTIONS OF SAID EXPLOSIVE CHARGE CONTACTING SAID CLOSURE MEANS; AND A DETONATOR MOUNTED FOR ROTATION IN SAID BODY AND POSITIONED SO AS TO ALIGN WITH SAID CLOSURE MEANS AND SAID EXPLOSIVE CHARGE UPON ROTATION OF SAID MISSILE ABOUT ITS LONGITUDINAL AXIS, SAID TEMPERATURE SENSITIVE MATERIAL IGNITING SAID TIME DELAY POWDER TRAIN AS A RESULT OF SAID NOISE REACHING SAID PREDETERMINED TEMPERATURE, SAID TIME DELAY POWDER TRAIN DETONATING SAID EXPLOSIVE CHARGE, DETONATION OF SAID EXPLOSIVE CHARGE EXPLODING THROUGH SAID CLOSURE MEANS AND CAUSING THE ALIGNED DETONATOR TO EXPLODE AND THUSLY INITIATE DESTRUCTION OF SAID MISSILE. 